Lennox G40UH(X) User Manual

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COOLING SEQUENCE OF OPERATION
NORMAL COOLING MODE ABNORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.
IS CONTROL OPERATING NORMALLY?
YES
SIGNAL POLARITY REVERSED AT LED.
POWER ON
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.
INTERRUPT MAIN POWER TO RESET CONTROL.
YES
IS POLARITY REVERSED?
ROLLOUT SWITCH MONITORED CONTINUOUSLY.
IS ROLLOUT SWITCH CLOSED?
CHECK FOR MAIN BURNER FLAME SENSE.
IS MAIN BURNER FLAME OFF?
LED: SLOW FLASH RATE REMAINS UNCHANGED
THROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FAN
ENERGIZED WITH 0-SECOND DELAY
(COOLING SPEED). EAC−H TERM. ENERGIZED.
COMPRESSOR OFF.
THERMOSTAT OPENS.
SYSTEM FAN AND ACC. TERM. OFF
WITH 0-SECOND DELAY.
NO
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON.
SIGNAL ROLL-OUT SWITCH OPEN AT LED.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL UNWANTED FLAME SENSED AT LED.
SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.
IS VOLTAGE
ABOVE 75 VOLTS?
LED SIGNALS WAITING ON CALL FROM
THERMOSTAT. CONTROL WILL NOT RESPOND
UNTIL VOLTAGE RISES ABOVE 75 VOLTS.
YES
YES
YES
NO
NO
NO

Lennox G40UH(X) Specifications

General

Brand	Lennox
Model	G40UH(X)
Category	Furnace
Language	English